Henri Cramail

Isocyanate-Free Routes to Polyurethanes and Poly(hydroxy Urethane)s

Greener routes to polyurethanes are required and arouse a growing interest in the academic and industrial communities. To this purpose, the depletion of fossil resources exacerbates the need of renewable materials. This review details two main routes to phosgene-free and isocyanate-free pathways to polyurethanes: the transurethanization and the cyclic carbonate/amine routes. A focus is also made on bio-based synthons toward non-phosgene and non-isocyanate PUs.

Synthesis of Biobased Polyurethane from Oleic and Ricinoleic Acids as the Renewable Resources via the AB-Type Self-Condensation Approach

Polyurethane (PU) from methyl oleate (derived from sunflower oil) and ricinoleic acid (derived from castor oil) was synthesized using the AB-type self-polycondensation approach for the first time. In the present work, three novel AB-type monomers, namely, a mixture of 10-hydroxy-9-methoxyoctadecanoyl azide/9-hydroxy-10-methoxyoctadecanoyl azide (HMODAz), 12-hydroxy-9-cis-octadecenoyl azide (HODEAz) and methyl-N-11-hydroxy-9-cis-heptadecen carbamate (MHHDC) were synthesized from methyl oleate and ricinoleic acid using simple reaction steps. Out of these, HMODAz and HODEAz monomers were polymerized by the acyl-azido and hydroxyl AB-type self-condensation approach, while MHHDC monomer was polymerized through AB-type self-condensation via transurethane reaction. The acyl-azido and hydroxyl self-condensations were carried out at various temperatures (50, 60, 80. and 110 degrees C) in bulk with and without catalyst. A FTIR study of the polymerization, using HMODAz at 80 degrees C without catalyst, indicates in situ formation of an intermediate isocyanate group in the first 15-30 min, and further onward, the molar mass increases as observed by SEC analysis. In the case of the MHHDC monomer, a transurethane reaction was used to obtain a similar PU (which was obtained by AB-type acyl-azido and hydroxyl self-condensation of HODEAz) in the presence of titanium tetrabutoxide as a catalyst at 130 degrees C. HMODAz, HODEAz, MHHDC, and corresponding polyurethanes were characterized by FTIR, (1)H NMR, (13)C NMR, and MALDI-TOF mass spectroscopy. Differential scanning calorimetric analysis of polyurethanes derived from HMODAz, HODEAz, and MHHDC showed two different glass transition temperatures for soft segments (at lower temperature) and hard segments (at higher temperature), indicating phase-separated morphology.

Reactivity of Metallocene Catalysts for Olefin Polymerization: Influence of Activator Nature and Structure

In this review, various synthetic and structural aspects of methylaluminoxane and the elementary processes involved in olefin polymerization, as identified by various spectroscopic techniques, are detailed. Various boron-based counterions and their interactions with metallocenium cations are discussed. A comparison between MAO and boron-based activators in terms of catalytic activity and polymer characteristics is made. Finally, the use of the above system in the polymerization of cationically polymerizable monomers and acrylates is discussed.

Structure–properties relationship of fatty acid-based thermoplastics as synthetic polymer mimics

Nowadays the use of vegetable oils as polymer precursors is the subject of growing interest in the academic and industrial communities. Many synthetic pathways can be pursued from natural vegetable oils to yield different functionalized derivatives – also called synthons – and polymers, such as polyesters, polyurethanes, polyamides, etc. Herein, we widely overview recent progress in the preparation of vegetable oil-based thermoplastic polymers and, more precisely, thermoplastic polyesters and polyurethanes. Extra focus is also placed on the synthesis sustainability of these polymeric materials via atom efficient techniques, “green” catalyses and processes. The achievable bio-sourced polymers cover a wide range of thermo-mechanical properties that can respond to most of the current applications of synthetic polymers.

Solubility in CO2 and carbonation studies of epoxidized fatty acid diesters: towards novel precursors for polyurethane synthesis

Novel linear polyurethanes were synthesized by bulk polyaddition of diamines with two vegetable-based biscarbonates produced from oleic acid methyl ester. Internal carbonated fatty acid diester (ICFAD) and terminal carbonated fatty acid diester (TCFAD) were obtained by the reaction of their epoxide precursors with CO2. Terminal epoxy fatty acid diester (TEFAD) was found to be more soluble and more reactive in CO2 than internal epoxy fatty acid diester (IEFAD). Polyurethanes obtained by polyaddition of TCFAD and ICFAD with diamines exhibit molecular weights up to 13 500 g mol−1 and glass transitions around −15 °C. Amide linkages were not observed when secondary diamine was used as the comonomer.

From Lignin‐derived Aromatic Compounds to Novel Biobased Polymers

Nowadays, the synthesis of (semi)aromatic polymers from lignin derivatives is of major interest, as aromatic compounds are key intermediates in the manufacture of polymers and lignin is the main source of aromatic biobased substrates. Phenols with a variety of chemical structures can be obtained from lignin deconstruction; among them, vanillin and ferulic acid are the main ones. Depending on the phenol substrates, different chemical modifications and polymerization pathways are developed, leading to (semi)aromatic polymers covering a wide range of thermomechanical properties. This review discusses the synthesis and properties of thermosets (vinyl ester resins, cyanate ester, epoxy, and benzoxazine resins) and thermoplastic polymers (polyesters, polyanhydrides, Schiff base polymers, polyacetals, polyoxalates, polycarbonates, acrylate polymers) prepared from vanillin, ferulic acid, guaiacol, syringaldehyde, or 4-hydroxybenzoic acid.

Novel green fatty acid-based bis-cyclic carbonates for the synthesis of isocyanate-free poly(hydroxyurethane amide)s

Fatty acid-based bis-cyclic 5-membered carbonates containing amide linkages were prepared from methyl 10-undecenoate. The reaction in bulk of these bio-based carbonates with a series of di-amines led to poly(hydroxyurethane amide)s with molar masses up to 31 000 g mol−1. As expected, the so-formed bio-based thermoplastic poly(hydroxyurethane)s exhibit amorphous to semi-crystalline features with respect to the chemical structure of the monomers used.

Optimization of the Bulk Heterojunction Composition for Enhanced Photovoltaic Properties: Correlation between the Molecular Weight of the Semiconducting Polymer and Device Performance

Herein we propose an approach toward the optimization of the photovoltaic performance of bulk heterojunctions by tuning the composition of the active layer with respect to the molecular weight of the semiconducting polymer. We used a poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) blend as a typical system and varied the molecular weight of the P3HT semiconducting polymer in order to determine its influence on the bulk heterojunction morphology as well as on the optoelectronic characteristics of the device. We have systematically mapped out the phase diagram for different molecular weight P3HTs blended with PCBM and observed the presence of a eutectic composition, which shifts to higher content of P3HT for lower molecular weight P3HTs. This shift inherent to the P3HT molecular weight is also apparent in the photovoltaic performance as the eutectic composition corresponds to the best of the photovoltaic properties. The P3HT molecular weight dependence of the eutectic composition is due to the molecular weight dependence of the P3HT crystallization behavior, which leads to dramatic morphological changes of the bulk heterojunction.

Fatty acid-based (bis) 6-membered cyclic carbonates as efficient isocyanate free poly(hydroxyurethane) precursors

(Bis) 6-membered cyclic carbonates were prepared from methyl 10-undecenoate, which is produced from ricinoleic acid, a main constituent of castor oil. Kinetic studies on these new fatty acid-based 6-membered cyclic carbonates revealed that they are much more reactive than their homologs, 5-membered ones (30 times). Poly(hydroxyurethane)s (PHUs) were then synthesized from these bis 6-membered cyclic carbonates at a temperature as low as room temperature and in the solvent or bulk. Unexpectedly, chemical gels were obtained. The latter were the consequence of side reactions of carbonate ring-opening with the hydroxyl groups of the formed poly(hydroxyurethane)s. Quenching with a large excess of hexylamine enabled the breaking-up of the gel with the formation of urea linkages.

Activated lipidic cyclic carbonates for non-isocyanate polyurethane synthesis

Activated 5-membered cyclic carbonates were prepared from glycerol and fatty acid derivatives. Ester and ether moieties were introduced in the β position to the cyclic carbonate, in order to enhance its reactivity towards amines. 1H NMR kinetic investigation of the aminolysis of these cyclic carbonates demonstrated a higher reactivity compared to the one of alkyl substituted cyclic carbonates. In the case of ester-activated carbonates, a reactivity similar to the one of 6-membered ring cyclic carbonates was observed. Moreover, these carbonates exhibited amidation side-reactions with amines that could be however prevented by decreasing the temperature to room temperature. Poly(hydroxyurethane)s (PHUs) were then synthesized from these activated 5-membered ring cyclic carbonates at 70 °C in DMF (1 mol L−1) and exhibited molar masses up to 13700 g mol−1 with Tg in the range −26 to −10 °C.